1. Field of the Invention
The present invention relates to a fiber-based cushion which can be used in, e.g., vehicles, furniture, and bedclothes and a method of manufacturing the same.
2. Description of the Related Art
Various types of materials are conventionally used as a cushion of a sheet of a vehicle and the like. Examples of the material are a palm rock using fibers of a palm, a synthetic resin foam such as a polyurethane foam, and cotton consisting of organic synthetic fibers. However, the palm rock is easily flattened because it has a large specific gravity and has a problem in source supply stability, and the polyurethane foam easily becomes stuffy because its air permeability is poor and is uncomfortable to sit in. The organic synthetic fiber cotton has a low hardness and is therefore easily flattened.
In recent years, therefore, a cushion material obtained by bonding crossing portions of three-dimensionally interwined organic synthetic fibers by a polyurethane resin has been developed and proposed in Published Unexamined Patent Application No. 61-158437. This cushion material has excellent air permeability, is not easily flattened, has high durability, and is light in weight.
In order to manufacture the cushion material obtained by bonding crossing portions of three-dimensionally interwined organic synthetic fibers by a polyurethane resin, the organic synthetic fibers are impregnated with a polyurethane prepolymer, and this polyurethane prepolymer is hardened. In this case, however, since the polyurethane prepolymer cannot be impregnated in the organic synthetic fibers because its viscosity is very high, it is diluted to adjust the viscosity.
1,1,1-trichloroethane or the like, however, which is used as an organic solvent has strong toxicity, it cannot be directly disposed in consideration of environmental conditions. Therefore, a large-scale salvage installation or the like is required. In addition, since hardening of the polyurethane prepolymer requires water vapor, an expensive installation such as a boiler is required.